In 2024, prompt engineering was the thing. In 2025, it was context engineering. I believe 2026 will be all about “harness engineering”. So I started a free newsletter about it. Below is an excerpt from the first issue: Coding agents are like slot machines, and I was hooked. But I didn’t just want to play the game - I wanted to “beat the house”. So I became obsessed: what changes could I make to win more often? To tilt the weights in my favor, so to speak. Early this year, a term emerged for the thing myself and others have been building: Harness engineering is the discipline of making AI coding agents reliable by engineering the system around the model - the workflows, specifications, validation loops, context strategies, tool interfaces, and governance mechanisms that make agents more deterministic and accountable. So what does a harness actually look like? The mental model I use is three nested loops: The outer loop runs at the project level. This is where you capture intent: specs, architecture docs, the knowledge base that agents pull from. It’s also where governance lives: human oversight, keeping the repo clean, making sure the codebase doesn’t rot over time. Think of it as the environment the agent works in. The orchestration loop runs per feature. Plan before you build - requirements, design, task breakdown - where each artifact constrains the next. Only once the plan is solid does implementation begin, one task at a time, each verified before the next starts. The inner loop runs per task. Write the code, verify it works, and if it doesn’t - feed the errors back and try again. How you structure that cycle determines whether the agent produces working software or confident garbage. This isn’t hypothetical. Each loop shows up clearly in real projects. Here’s one case study per loop. Full writeup here: https://codagent.beehiiv.com/p/slot-machines-and-safety-nets . If you found this article interesting, please subscribe. I would love some feedback on the article! Curious if others building with coding agents are seeing similar patterns, or if you’ve landed on different approaches. Also, to be transparent: I am building tools around this idea (free + open source), which I mention at the end of the full writeup. submitted by /u/paulcaplan
Originally posted by u/paulcaplan on r/ClaudeCode